Hybrid point to multipoint communication system

ABSTRACT

Methods and systems for hybrid point to multipoint communication systems, including the steps of: determining transmission synchronization and bandwidth allocation between a first wireless client and a second wireless client communicating via a common communication channel; transmitting a download multi carrier transmission, via a shared signal wired distribution line, wherein the download multi carrier transmission comprises the determined transmission synchronization and bandwidth allocation; receiving the download multi carrier transmission by a first hybrid converter and by a second hybrid converter connected to the shared signal wired distribution line; shifting the frequency of the download multi carrier transmission from a wired distribution line frequency to a wireless frequency in the first hybrid converter and in the second hybrid converter; and transmitting the frequency-shifted download multi carrier transmission to the air from the first hybrid converter and from the second hybrid converter.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/739,429, filed on Nov. 25, 2005, the entirecontent of which is incorporated herein by reference.

This application is related to the following US Patent Applicationsfiled concurrently herewith herein incorporated by reference in theirentirety. U.S. patent application Ser. No. 11/602,967, filed on Nov. 23,2006; U.S. patent application Ser. No. 11/603,178, filed on Nov. 23,2006; U.S. patent application Ser. No. 11/603,177, filed on Nov. 23,2006; and U.S. patent application Ser. No. 11/603,080, filed on Nov. 23,2006.

BACKGROUND

The embodiments of the present invention relate to communication systemsand, more particularly, to methods and corresponding systems for hybridwired-wireless and wireless-wireless, point-to-multipoint communication,featuring a shared channel, discrete multi-tone modulation, and wirelesstransmission.

Basic principles and details relating to hybrid wired-wirelesspoint-to-multipoint communication systems needed for properlyunderstanding the embodiments of the present invention are providedherein. Complete theoretical descriptions, details, explanations,examples, and applications of these and related subjects and phenomenaare readily available in standard references in the fields of digitaltelecommunication.

Known wireless modems take information from customer modems (Cable/CATVmodem, xDSL modem or PON modem) and remodulate it in the air between thewire's endpoint and various wireless devices. These wirelesstechnologies may vary and include technologies such as WiFi, WiMAX,BlueTooth, ZigBee and UWB.

Cable modems mostly use the DOCSIS standards for transferring data inparallel with dedicated CATV channels, which transfer the video channelsover coax cables. Various modulations can be used to carry the data overthe coax, while the most common modulation used today over Coax issingle carrier. In xDSL modems a similar approach is used for carryingdata over twisted pairs used by the PSTN infrastructure. The most commonmodulation used in xDSL is DMT/OFDM, even though single carrier QAMmodulations are used as well in certain standards.

Some embodiments of the invention feature multi-carrier modulation.Multi-carrier modulation systems generally involve a data signal made ofsuccessive symbols, split into several lower rate signals, eachassociated with a sub-carrier and resulting in a long symbol time incomparison to the expected multipath delay spread. Orthogonal frequencydivision modulation (OFDM) is a multi-carrier modulation scheme, whichmaps data symbols onto N orthogonal sub-carriers, separated by adistance of 1/T, and where T is the useful symbol duration. In OFDM,cyclic guard intervals are frequently used to improve performance in thepresence of a multipath channel. OFDM has become attractive for wirelesscommunications due to its high spectral efficiency and resistance tonoise and multipath effects. OFDM has been the foundation of a number ofwireless broadcast standards, some of them providing for SingleFrequency Network (SFN) operation, in which a number of transmittersoperate in simulcast manner.

OFDMA is the “multi-user” version of OFDM. Each OFDMA user transmitssymbols using subcarriers that remain orthogonal to those of otherusers.

The orthogonal frequency division multiple access (OFDMA) system, amultiple access system designed for simultaneous access by multipleusers, is applied to OFDM. OFDMA divides an allocated frequency bandinto N subcarriers and allocates them to groups, for simultaneous use bymultiple links. Supporting high rate applications, multiple subcarriersmay be assigned to a single user. On the forward link from a basestation to a plurality of users, the subcarrier groups, allocated to therespective mobile stations, are transferred simultaneously, while at thesame time synchronizing with one another, and thereby guaranteeingmutual orthogonality of the subcarriers.

BRIEF SUMMARY

The disclosed embodiments may be readily implemented using standardhardware. Moreover, the system of the present invention may beapplicable as a centralized system or a decentralized system.

Implementation of the method and corresponding system of the presentinvention involves performing or completing selected tasks or stepsmanually, semi-automatically, fully automatically, and/or, a combinationthereof. Moreover, according to actual instrumentation and/or equipmentused for implementing a particular embodiment of the disclosed methodand corresponding system, several selected steps of the embodiments ofthe present invention could be performed by hardware, by softwarerunning on any operating system of any firmware, or a combinationthereof. In particular, as hardware, selected steps of the inventioncould be performed by a computerized network, a computer, a computerchip, an electronic circuit, hard-wired circuitry, or a combinationthereof, involving a plurality of digital and/or analog, electricaland/or electronic, components, operations, and protocols. Additionally,or alternatively, as software, selected steps of the invention may beperformed by a data processor, such as a computing platform, executing aplurality of computer program types of software instructions orprotocols using any suitable computer operating system.

It is to be understood that the scope of the present invention is notlimited in its application by details relating to the order or sequenceof steps of operation, or implementation of the method; furthermore, itsapplication/use is not limited by details relating to construction,arrangement, and, composition of the components of the device, all ofwhich are set forth in the following description, drawings, or examples.While specific steps, configurations and arrangements are discussed, itis to be understood that this is for illustrative purposes only. Aperson skilled in the relevant art will recognize that other steps,configurations and arrangements can be used without departing from thespirit and scope of the present invention.

The present invention is capable of having further embodiments or ofbeing practiced, or carried out, in other various ways. Also, it is tobe understood that the phraseology, terminology, and, notations foundherein are for the purpose of description and should not be regarded aslimiting the scope of the present invention.

In the following description of the method of the present invention,included are only main or principal steps needed for sufficientlyunderstanding proper ‘enabling’ utilization and implementation of thedisclosed methods and corresponding systems. Accordingly, descriptionsof the various required or optional minor, intermediate, and/or, substeps, which are readily known by one of ordinary skill in the art,and/or, which are available in the prior art and technical literaturerelating to digital communication, are not included herein.

The present invention discloses five sets of embodiments. Some or all ofthese five sets of embodiments may refer to the same drawings. It is tobe understood that each of these five sets of disclosed embodiments maybe implemented independently or implemented in conjunction with othersets. Therefore, any information disclosed in a specific set ofembodiments may or may not be relevant to the other sets of disclosedembodiments, without limiting the scope of the present invention.

One embodiment of the hybrid system of the present invention is able togenerate a ubiquitous indoor and outdoor wireless access cloud overlarge areas by using multiple transmission and reception OFDM or OFDMAsources as disclosed below. As a result, it is possible to createmetro-level, commercial, and wireless point-to-multipoint hot zones,such as WiMAX hot zones. Moreover, this embodiment of the hybrid systemof the present invention successfully enables a CATV operator to extendhis/her distribution network to include wireless access services, forexample, WiMAX (802.16d/e) wireless access services.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of the present invention are herein described, by way ofexample only, with reference to the accompanying drawings. With specificreference now to the drawings in detail, it is stressed that theparticulars shown are by way of example and for purposes of illustrativediscussion of the embodiments of the present invention only, and arepresented in the cause of providing what is believed to be the mostuseful and readily understood description of the principles andconceptual aspects of the embodiments. In this regard, no attempt ismade to show structural details of the embodiments in more detail thanis necessary for a fundamental understanding of the invention, thedescription taken with the drawings making apparent to those skilled inthe art how the several forms of the invention may be embodied inpractice. In the drawings:

FIG. 1A is a schematic illustration of a wired-wirelesspoint-to-multipoint communication system operated outdoors and indoors,in accordance with the present invention;

FIG. 1B is a schematic illustration of a wired-wireless and wired-wiredpoint-to-multipoint communication system operated indoors, in accordancewith the present invention;

FIG. 1C is a schematic illustration of a wired-wireless and wired-wiredpoint-to-multipoint communication system operated outdoors and indoors,in accordance with the present invention;

FIG. 1D is a schematic illustration of a wired-wired point-to-multipointcommunication system operated indoors, in accordance with the presentinvention;

FIG. 1E is a schematic illustration of a wired-wired point-to-multipointcommunication system operated in a single indoor area, in accordancewith the present invention;

FIG. 1F is a schematic illustration of a wired-wired point-to-multipointcommunication system operated indoors, in accordance with the presentinvention;

FIG. 1G is a schematic illustration of a wireless-wirelesspoint-to-multipoint communication system, wherein a centralizedsynchronizing communication controller is communicating through the air,in accordance with the present invention;

FIGS. 2A-B are schematic diagrams illustrating a hybrid converter, inaccordance with embodiments of the present invention;

FIG. 3 is a schematic illustration of OFDM or OFDMA signal combining atthe sub-carrier level, in accordance with one embodiment of the presentinvention;

FIG. 4A-D are schematic illustrations of OFDM or OFDMA multiple downlinkchannels, in accordance with embodiments of the present invention;

FIG. 5 is a schematic diagram illustrating an exemplary switched hybridconverter, in support of TDD Wireless point-to-multipoint Hybrid systemoperation, in accordance with one embodiment of the present invention;

FIG. 6 is a schematic diagram illustrating an uplink OFDMA thermal noisebuildup filter, in accordance with one embodiment of the presentinvention;

FIG. 7 is a schematic illustration of combining simulcast and singlecast in the same OFDMA channel by the utilization of sub-channelization,in accordance with one embodiment of the present invention;

FIG. 8 is a schematic illustration of combining simulcast and singlecast in the same OFDM/OFDMA channel by the utilization of time division,in accordance with one embodiment of the present invention;

FIGS. 9A-B are schematic illustrations of the formation of wirelessaccess fields featuring different dimensions, in accordance with oneembodiment of the present invention;

FIGS. 10A-18E are flowcharts illustrating various methods in accordancewith some of the embodiments of the present invention;

DETAILED DESCRIPTION

Hereinafter, the terms clients, and/or users, and/or wireless users,and/or end-stations, and/or wireless broadband subscriber stations,refer to any device that communicates with the centralized synchronizingcommunication controller of the present invention.

Hereinafter, the term “wired distribution line” refers to any sharedphysical line that distributes signals through a medium which is not theair, including, but not limited to, coax lines, fiber optics lines,twisted pair lines, or any combination of these and/or other mediums.

Hereinafter the term ‘OFDM’, also known as COFDM, refers to anyorthogonal multi-carrier modulation.

Hereinafter the term ‘OFDMA’ refers to any orthogonal multi-carriermodulation with frequency sub-channelization capabilities.

Hereinafter the term “orthogonal multi-carrier modulation” also refersto OFDM, OFDMA, and COFDM.

Hereinafter the term “IEEE 802.16” refers to any wireless point tomultipoint communication system with a centralized MAC, and employingmulti-carrier modulation.

Hereinafter the term “IEEE 802.16e” refers to any wireless point tomultipoint communication system with a centralized MAC, and employingmulti-carrier modulation with frequency sub-channelization capabilities.

Hereinafter the term “hybrid converter” refers to a device that adaptsbetween two mediums, such as but not limited to: a) a frequencyup-converter and/or down-converter that shifts a first frequency band ofan input signal from a wired medium to a second frequency band of awireless medium, and/or from a first frequency band of an input signalfrom a wireless medium to a second frequency band of a wired medium; b)a frequency converter between a first wireless frequency and a secondwireless frequency and vice versa; c) a converter between a wired signaland a wireless signal and vice versa, wherein the wired frequency is thesame as the wireless frequency, such as coax to wireless mediumconverter, or fiber to wireless medium converter, wherein the fiber towireless medium converter includes an optical to electrical converter.

Hereinafter the term “centralized synchronizing communicationcontroller” refers to any centralized-communication device capable ofinjecting a common communication signal into a wired distribution lineand communicating, in a synchronized manner, with at least two clients.The centralized synchronizing communication controller achievessynchronization and bandwidth allocation with the at least two clientsusing a synchronizing Medium Access Controller (MAC). Without limitingthe scope of the invention, the following are examples of centralizedsynchronizing communication controllers: base stations, access points,and Cable Modem Termination Systems (CMTS). The clients may be wiredclients, wireless clients, or a combination thereof.

Hereinafter the term “MAP” refers to the transmission slots allocated bya MAC in order to synchronize the uplink and downlink transmissions ofall participating clients. It is to be understood that the term MAP isnot limited to WIMAX applications although it is readily used by them.

The first set of disclosed embodiments is described herein.

Implementation of the disclosed embodiments enables the installation ofseveral inexpensive stations, with greater coverage, and the locating ofall modems in one central location. Locating all modems in one centrallocation may lower maintenance costs, and in certain circumstances, evenreduce the number of required modems.

In one embodiment to the first set of disclosed embodiments, the systemis a multi-location communication system. In this alternativeembodiment, the MAC and PHY are located at a central point.Alternatively, the MAC is located at a central point and each PHY islocated at each end-station. This alternative embodiment enables thesetting up of communication centers at remote sites, wherein thecommunication centers feature all or most of the logic and setting up ofthe end-point stations.

The disclosed embodiments may use SFN with one central modem and aplurality of antennas. Moreover, the embodiments cut costs whileobtaining improved coverage—the result of using many antennas.

The first set of disclosed embodiments features a unique method andcorresponding system. The unique method and corresponding system enablean efficient means for a centralizing communication node to communicatewith a plurality of wireless broadband subscriber stations, in apoint-to-multipoint fashion, and using multi-carrier modulation, such asOFDM or OFDMA modulations.

One embodiment of the disclosed Hybrid System communicates with thewireless users via at least two types of mediums at the same time. Thefirst type of medium is a wired medium. Examples of wired mediums arecoaxial lines (such as CATV), fiber optics, twisted pair, and copper.The second type of medium is the air. Examples of transmissions throughthe air include any wireless/RF transmissions such as WiFi and WIMAX.

In one embodiment of the invention, OFDM or OFDMA modulation isimplemented. This embodiment has the ability to transmit/receive thesame OFDM or OFDMA physical layer modulation signal via both the wiredand the wireless portions of the network. As a result, the Hybridcentral node becomes capable of injecting the downlink signal into thewired portion first; then the same signal is up-converted to higherfrequencies before being transmitted to the subscriber via the wirelessportion of the network (and vice versa for the uplink direction). TheHybrid System circumvents the need for two separate physical layermodulation signals for the wired and wireless portions of the network,by using a shared physical layer signal.

Moreover, the usage of long symbol times and long symbol guard times,both inherent characteristics of OFDM and OFDMA modulation schemes, asdisclosed herein, provides a method for simultaneously overcoming boththe multipath problem, typical to the wireless medium, and theRF/Optical reflection problem, as well as the impulse noise problem,that are typical to the wired medium.

Moreover, the usage of a large number of subcarriers, which is aninherent characteristic of OFDM and OFDMA modulation schemes, asdisclosed in the present invention, is a method for simultaneouslyovercoming the narrowband interference problem that is typical of thewireless medium and the narrowband interference problem that is typicalof the wired medium.

The use of synchronizing MAC with the disclosed hybrid system preventsthe problem of hidden stations. Examples of MAC's featuring centralizedsynchronization and scheduling, are IEEE 802.16d/e MAC, WIBRO (developedby the Korean telecoms industry), and HIPERMAN (High Performance RadioMetropolitan Area Network, created by the European TelecommunicationsStandards Institute (ETSI) Broadband Radio Access Networks (BRAN)group).

Referring to the figures, FIG. 1A illustrates an embodiment of a hybridwired-wireless point-to-multipoint communication system. Centralizedsynchronizing communication controller 7, which may also be referred toas a hybrid base station or centralized hybrid communication node, islocated inside an operator's distribution node 8. Centralizedsynchronizing communication controller 7 is connected to the operator'sbackhaul network 2 on one side, and to a section of the operator'sshared signal wired distribution line 6 on the other side. As definedabove, the wired distribution line 6 may include, but is not limited to,a fiber optics line, coax line, twisted pair line, or any combination ofthese or other mediums. Wired distribution line 6 may be a passive wiredline, or it may contain amplifiers in both uplink and downlinkdirections. Wired distribution line 6 may be constructed according toany topology (tree, star, other, or combinations thereof), provided thatall the branches of the section driven by Centralized synchronizingcommunication controller 7 share the same spectrum, or in other words,that any signal on the section be present at all of its branches at anygiven time.

Without limiting the scope of the present invention, an example of wireddistribution line 6 is the distribution portion of an HCF (Hybrid CoaxFiber) network commonly used with CATV operators. Another example istransmitting the common signal over telephone line twisted pair, suchthat the hybrid converters are placed along the twisted pair line.

In one embodiment, the common signal is transmitted over multipletelephone line twisted pairs such that the hybrid converters are placedalong the twisted pairs lines, and such that all of the twisted pairslines are electrically combined near the centralized synchronizingcommunication controller.

An advantage of the disclosed embodiments of the present invention isthat the wireless clients may be standard mobile WIMAX clients, such asIEEE 802.16e.

A plurality of alternative architecture embodiments are available to acommunication system in accordance with the present invention. Allalternative embodiments are included in the scope of the presentinvention. FIGS. 1A to 1G illustrate some non-limiting alternativearchitecture embodiment examples that may be used with almost all of theembodiments herein disclosed.

FIG. 1A illustrates a wired-wireless point-to-multipoint communicationsystem operated outdoors and indoors 1. In this case, the shared signalwired distribution line 6 may comprise, but is not limited to, coaxline, fiber-optics line, and a twisted pair line.

FIG. 1B illustrates a wired-wireless and wired-wired point-to-multipointcommunication system operated indoors 1. In this case, the shared signalwired distribution line 6 may comprise, but is not limited to: coaxline, fiber-optics line, and a twisted pair line.

FIG. 1C illustrates a wired-wireless and wired-wired point-to-multipointcommunication system operated outdoors and indoors 1. In this case, theshared signal wired distribution line 6 a comprises multipleshort-circuited twisted pair lines 6 c, 6 d, and 6 e.

FIG. 1D illustrates a wired-wired point-to-multipoint communicationsystem operated indoors 1 a, 1 b. In this case, the wired distributionline 6 may comprise, but is not limited to: coax line, fiber-opticsline, and a twisted pair line.

FIG. 1E illustrates a wired-wired point-to-multipoint communicationsystem operated in a single indoor area 1. In this case, the wireddistribution line 6 may comprise, but is not limited to, coax line,fiber-optics line, and a twisted pair line.

FIG. 1F illustrates a wired-wired point-to-multipoint communicationsystem operated indoors 1 a, 1 b. In this case, the shared signal wireddistribution line 6 a comprises multiple short-circuited twisted pairlines 6 c, 6 d.

FIG. 1G illustrates a wireless-wireless point-to-multipointcommunication system, wherein centralized synchronizing communicationcontroller 7 is communicating through the air (6 x, 6 y) with aplurality of hybrid converters (20 a, 21 a) that perform a frequencyshift and communicate with a plurality of wireless clients.

In one embodiment of the invention, the centralized synchronizingcommunication controller 7 features a centralized MAC (Medium AccessControl) layer that controls the uplink and downlink access to theshared physical layer 6 (also referred to as the wired distributionline) for the plurality of users 4, 50, 51 being serviced by thecentralized synchronizing communication controller 7. Users 4, 50, 51may also be herein referred to as subscriber devices. Without limitingthe scope of the present invention, an example of MAC is the IEEE 802.16MAC layer.

In one embodiment of the invention, the centralized synchronizingcommunication controller 7 modulates the downlink transmission usingmulti-carrier modulation such as a OFDM or OFDMA modulation scheme,which can be used to transport the signal over both wired medium andwireless medium. Examples of modulation schemes are the IEEE 802.16 PHYlayer, or IEEE 802.11 PHY layer. The modulated signal may be placed inan appropriate portion of the spectrum supported by the specific wireddistribution line 6, and may reach directly to the plurality of hybridwired-wireless converters, referred to as hybrid converters 20, 21. Forexample, the modulated signal may be placed in optical frequencies inthe case of fiber optic line, and downlink RF frequencies in the rangeof 45-1000 Mhz in the case of a CATV coaxial line.

FIG. 2A illustrates one non-limiting embodiment of a hybrid converter.In the embodiment, the frequency used in transmissions over the wireddistribution system is different from the frequency used in the wirelesstransmission. Hybrid converters 20, 21 receive a downlink modulatedsignal 110 directly from the wired distribution line 6, and use an up-or down-conversion method to convert signal 110 to an appropriatewireless downlink RF frequency. The RF frequency is then transmitted tothe air 112, 30, 31, 32, 33 via antenna 121. For example, hybridconverters may convert the wired signal to the wireless frequencies 0.7,2.3, 2.5, 3.5, 5.8 Ghz in the case of IEEE 802.16, or 2.4, 5.2, 5.8 Ghzin the case of IEEE 802.11. It is to be understood that before and/orafter the up- and/or down-conversion 140, 141, some filtration,amplification and/or optical-to-electrical conversion (in the case offiber optics medium) may be implemented by using an optional elementillustrated in the figure as element 130. Moreover, it is to beunderstood that the system may operate a large amount of hybridconverters with or without the use of the filter disclosed herein.

FIG. 2B illustrates another non-limiting embodiment of the hybridconverters (20, 21), wherein the hybrid converter converts between twodifferent mediums, such as, but not limited to: coax and wireless, fiberand wireless, twisted pair and wireless, and fiber and coax. The hybridconverter illustrated in FIG. 2B does not perform a frequency conversionand therefore does not comprise up and down converters, such as up anddown converters 140 and 141 illustrated in FIG. 2A.

Referring again to FIGS. 1A-1C, aired transmissions 30, 31, 32, 33 reachall users 4, 50, 51, and therefore allow the centralized synchronizingcommunication controller 7 to both directly communicate with, andsynchronize, them via the point-to-multipoint MAC. It is to be notedthat the hybrid converters may not be aware of the actual signalmodulation or upper MAC layers, and may be implemented as simplenon-regenerative relays of communication between the point-to-multipointend nodes. In this case, only the centralized synchronizingcommunication controller 7 and users 4, 50, 51 are performing the actualmodulation and demodulation, so that the hybrid converters 20, 21 can bekept simple and cost effective.

Implementing the uplink direction may be performed similarly toimplementing the downlink direction, the only difference being that thewireless signals 113, 30, 31, 32, 33 from users 4, 50, 51 are up or downconverted 141 to a signal 111 that is placed in an appropriate portionof the uplink spectrum, and supported by the specific wired distributionline 6. Examples of a supported uplink spectrum include opticalfrequencies in the case of fiber optic line, or, in the case of CATVcoaxial line, uplink RF frequencies in the range of 5-65 Mhz.

It is to be understood that hybrid converter 20, 21 may be operated ineither TDD or FDD modes, depending on the selection of actual PHY andMAC layers. Moreover, it is to be understood that a wired converter,also referred to as wired modem 10, may be operated to support wiredsubscribers 9.

FIG. 1B illustrates a system having three wired modems 10 connected to 3wired subscribers . . . . The communication with the wired convertersand/or wired modems 10 may be done similarly to what was described inthe wireless clients section above. Centralized synchronizingcommunication controller may support both wired and wireless clientsinterchangeably.

As known in the relevant art, when implementing the wired medium withfiber optics, the uplink and downlink feature approximately the samebandwidth. As a result, prior art solutions which implement OFDM overfiber optics are not useful for coax line because prior art solutions donot disclose asymmetric uplink and downlink transmissions. Moreover,prior art solutions do not solve the noise build-up in the uplinkdirection, nor the hidden station problem in SFN.

The embodiments of the present invention successfully overcome thelimitations, and widen the scope of presently known hybrid systemconfigurations over coax by a selection of an appropriate wireless PHYwhich also solves the coax lines problems of impulse noise and narrowband noise.

Another embodiment of the present invention discloses the use ofsub-channelization for the uplink direction as a method of overcomingthe thermal noise buildup associated with the return channel of a hybridsystem. In one embodiment, the IEEE 802.16d/e standardsub-channelization may be used.

There are cases where the return channel in a hybrid system suffers froma thermal noise buildup that is caused by the simultaneous transmissionof multiple hybrid converters in the uplink direction 111. Switching offthe hybrid converters may not be possible because each user uses adifferent sub-channel, as in the case of WIMAX. The embodiments of thepresent invention disclose two optional solutions to the problem ofthermal noise buildup: The first solution is the channel filter asdisclosed below. The second solution features the use of OFDMAmodulation wherein each user uses only a sub-set of the sub-carrierswhen transmitting up stream, i.e. the transmitted energy is concentratedin bandwidth, which is narrow in relation to the total bandwidth of thechannel. In addition, by using the MAP, each user transmits using adifferent sub-set. As a result, by using a concentration gain, theuplink uses only a small set of sub-channels. Therefore, because of theconcentration gain, the combination of OFDMA over coax introduces theunexpected result of solving the problem of thermal noise buildup up toa predefined number of users.

For example, in a 10 Mhz channelization IEEE 802.16e transmission, eachconverter contributes its 10 Mhz thermal noise to the overall noisepicked by centralized synchronizing communication controller 7 receiver,so that the total sensitivity of centralized synchronizing communicationcontroller 7 is degraded by the amount of:10*log [Number of Hybrid Converters per uplink channel] dB

This sensitivity degradation can cause the downlink and uplinkdirections to become asymmetrically sensitive, which is usuallyunwanted, since the hybrid system is designed to support bi-directionalcommunication.

The use of the sub-channelization in the uplink direction solves theproblem. For example, in the case of IEEE 802.16d/e OFDMA PHY and a 10Mhz 802.16e channel, the standard describes 35 simultaneous sub-channelsin the PUSC mode. If the wireless subscriber is concentrating its powerover 1/35 of the total uplink bandwidth (about 300 KHz) over onesub-channel, then it has a concentration gain of:10*log [Number of sub-channels in uplink channel] dB=10*log [35] dB=15dB

Assuming that the transmitted power budget of the hybrid converter isthe same as the transmitted power budget of the wireless subscriber(which is reasonable to assume, since the hybrid converter is a smalland cheap device), in order to produce a symmetrical link, the uplinkthermal noise degradation should be equal to the uplink concentrationgain, since in this case the uplink concentration gain advantage overthe downlink is exactly balanced by the thermal buildup degradationeffect10*log [35] dB=10*log [Number of Hybrid Converters per uplink channel]dB

The disclosed embodiment is able to place up to 35 hybrid converters onthe same OFDMA Hybrid system's channel, given the above examples andassumptions, without limiting the uplink direction in respect to thedownlink direction's range.

Referring to FIGS. 4A-4B, in one embodiment of the invention, apoint-to-multipoint broadcasting MAC that utilizes a downlink/uplinkMAP, such as the IEEE 802.16d/e MAC, may be used in order to reach andsynchronize a plurality of broadband wireless users via a hybridwired-wireless medium. The point-to-multipoint broadcasting MAC utilizesa downlink/uplink MAP 302, 303, such as the IEEE 802.16d/e MAC, as amethod of reaching and synchronizing a plurality of broadband wirelesssubscribers via a hybrid wired-wireless medium as illustrated by priorart FIG. 4A.

Referring again to FIG. 2A, in one embodiment of the invention, a TDD(Time Domain Duplex) transmission scheme is implemented, where thewireless downlink 112 frequency is shared with the uplink 113 frequency.In that case, when the MAC starts to transmit the downlink MAP 302, allof the hybrid converters must enable the downlink transmission path (thepath converting 110 signal to 112 signal via mixer 140), and disable theuplink transmission path (the path converting 113 signal to 111 signalvia mixer 141). An optional embodiment comprises the step of sensing thestart of the downlink MAP Preamble transmission energy coming from thecentralized synchronizing communication controller 7, and switching tothe correct direction, or alternatively by using an explicit switchingcommand from the centralized synchronizing communication controller 7.Referring again to FIG. 4B, the opposite happens (meaning, enabling theuplink path and disabling the downlink path in the hybrid converters)when the uplink 305 time period begins; this event is triggered eitherby the hybrid converters' counting time beginning when the downlink MAPPreamble transmission energy detection event occurs, or alternatively byan explicit switching command from the centralized synchronizingcommunication controller 7.

Referring again to the figures, FIG. 5 is a schematic diagramillustrating an example of a switched hybrid converter, in support ofthe above described TDD Wireless point-to-multipoint Hybrid systemoperation. Exemplified is Block 500 performing the power detection andcontrol switching control.

It is to be understood that non-switched operation of the hybridconverters (meaning that both uplink path and downlink path in thehybrid converters are always enabled) for both wireless TDD or wirelessFDD modes is possible, however, it requires the use of more Duplexers,and is susceptible to uplink/downlink RF coupling effects in the case ofTDD operation.

It is to be understood that the wired medium may be composed of morethan one wired section, such as, but not limited to, a first fiberoptics section converted to a second coaxial section.

Referring back to the drawings, FIGS. 10A-10C illustrate embodimentshaving the following steps: In step 1002, determining transmissionsynchronization and bandwidth allocation between a first wireless clientand a second wireless client communicating via a common communicationchannel, by using a wireless point to multi point centralizedsynchronizing communication controller; In step 1004, transmitting adownload multi carrier transmission, via a shared signal wireddistribution line, wherein the download multi carrier transmissioncomprises the determined transmission synchronization and bandwidthallocation; In step 1006, receiving the download multi carriertransmission by a first hybrid converter and by a second hybridconverter connected to the shared signal wired distribution line; Instep 1008, shifting the frequency of the download multi carriertransmission from a wired distribution line frequency to a wirelessfrequency in the first hybrid converter and in the second hybridconverter; And in step 1010, transmitting the frequency-shifted downloadmulti carrier transmission to the air from the first hybrid converterand from the second hybrid converter.

Continuing 1012 in FIG. 10B, the following optional steps areillustrated: In steps 1014 and 1016, receiving by the first wirelessclient the frequency-shifted download multi carrier transmission fromthe first hybrid converter, and receiving by the second wireless clientthe frequency-shifted download multi carrier transmission from thesecond hybrid converter; And in step 1016, transmitting an upload multicarrier transmission to the air, by the first wireless client, accordingto the determined transmission synchronization and bandwidth allocation.

Optional steps 1020, 1022, and 1024 illustrate the following: receivingthe upload multi carrier transmission by the first hybrid converter;shifting the frequency of the received upload multi carrier transmissionfrom the wireless frequency to the wired distribution line frequency;and receiving the frequency-shifted upload multi carrier transmission,via the shared signal wired distribution line, by the wireless point tomulti point centralized synchronizing communication controller.

Referring again to FIGS. 10A-10B, in one embodiment, the upload multicarrier transmission is modulated by OFDMA and uses an amount ofsub-channels that is smaller than the entire composition of the OFDMAchannel. In one embodiment, the upload multi carrier transmission ismodulated by OFDMA and uses one sub-channel. In one embodiment, thedownload multi carrier transmission and the upload multi carriertransmission further comprise payloads.

Referring again to FIGS. 10A-10B, in one embodiment, the multi carriertransmissions are modulated by an OFDM or an OFDMA modulation, and thecentralized synchronizing communication controller comprises a MAC usedby an IEEE 802.16 orthogonal multi carrier modulation. In oneembodiment, the wireless clients are standard IEEE 802.16 orthogonalmulti carrier modulation mobile clients.

It is to be noted that the term “frequency” as used herein (such as: afirst signal having a first frequency) usually refers to achannel-frequency or to a sub-channel-frequency, i.e. the term frequencyusually does not imply a single frequency but rather refers to a set offrequencies which are used for transmitting a required signal.

Referring now to FIG. 10C, in one embodiment, the first and the secondhybrid converters have at least partially overlapping coverage areas andthe first wireless client is located in the overlapping coverage area.

Continuing 1012 in FIG. 10C, the following optional steps areillustrated: In step 1026, receiving by the first wireless client asuperposition of the transmitted frequency-shifted multi carriertransmissions from the first and from the second hybrid converters; andin step 1028, transmitting an upload multi carrier transmission to theair by the first wireless client.

Optional steps 1030 and 1032 illustrate the following: receiving theupload multi carrier transmission by the first and by the second hybridconverters, shifting the frequency of the upload multi carriertransmission from the wireless frequency to the wired distribution linefrequency; and receiving a superposition of the frequency-shifted uploadmulti carrier transmission from the first and the second hybridconverters, via the wired distribution line, by the wireless point tomulti point centralized synchronizing communication controller.

The meaning of overlapping coverage in accordance with one embodiment isthe existence of at least one spatial location that conforms with thecriteria that each signal is above the thermal threshold at saidlocation.

Referring back to the drawings, FIGS. 11A-11B illustrate embodimentshaving the following steps: In step 1102, determining transmissionsynchronization and bandwidth allocation between a first wireless clientand a second wireless client communicating via a common communicationchannel, by using a wireless point to multi point centralizedsynchronizing communication controller; In step 1104, transmitting adownload multi carrier transmission, via a shared signal wireddistribution line, wherein the download multi carrier transmissioncomprises the determined transmission synchronization and bandwidthallocation; In step 1106, receiving the download multi carriertransmission by a first hybrid converter and by a second hybridconverter connected to the shared signal wired distribution line; Instep 1108, converting the download multi carrier transmissions, in thefirst hybrid converter and in the second hybrid converter, from a wireddistribution line signal to a wireless signal without changing thefrequency of the download multi carrier transmissions; And in step 1110,transmitting the converted download multi carrier transmissions to theair from the first hybrid converter and from the second hybridconverter.

Continuing 1116 in FIG. 11B, the following optional steps areillustrated: In steps 1118 and 1120, receiving by the first wirelessclient the converted download multi carrier transmission from the firsthybrid converter, and receiving by a second wireless client theconverted download multi carrier transmission from the second hybridconverter; And in step 1122, transmitting an upload multi carriertransmission to the air by the first wireless client according to thedetermined transmission synchronization and bandwidth allocation.

Optional steps 1124, 1126 and 1128, illustrate the following: receivingthe upload multi carrier transmission by the first hybrid converter;converting the received upload multi carrier transmission from awireless signal to a wired distribution line signal without changing thefrequency of the multi carrier transmission; and receiving the convertedreceived upload multi carrier transmission, via the shared signal wireddistribution line, by the wireless point to multi point centralizedsynchronizing communication controller.

Referring again to FIGS. 11A-11B, in one embodiment, the download multicarrier transmission and the upload multi carrier transmission furthercomprise payloads. In one embodiment, the wireless clients are standardIEEE 802.16 orthogonal multi carrier modulation mobile clients. In oneembodiment, the upload transmission is modulated by OFDMA and uses anamount of sub-channels that is smaller than the entire composition ofthe OFDMA channel. In one embodiment, the upload multi carriertransmission is modulated by OFDMA and uses one sub-channel.

Referring again to FIG. 11A, in one embodiment, the first and the secondhybrid converters have at least partially overlapping coverage areas andthe first wireless client is located in the overlapping coverage area.

Continuing 1116 in FIG. 11A, the following optional steps areillustrated: In step 1112, receiving by the first wireless client asuperposition of the transmitted converted download multi carriertransmissions from the first and the second hybrid converters; And instep 1114, transmitting an upload multi carrier transmission to the airaccording to the determined transmissions synchronization and bandwidthallocation, by the first wireless client.

Referring back to the drawings, FIG. 12 illustrates embodiments havingthe following steps: In step 1202, determining transmissionssynchronization and bandwidth allocation between at least two wiredclients communicating via a common communication channel, by using apoint to multi point centralized synchronizing communication controllerdesigned for air interface; In step 1204, transmitting a downloadtransmission by using a multi carrier signal designed for air interface,via a shared signal wired distribution line, wherein the downloadtransmission comprises the determined transmission synchronization andbandwidth allocation; And in step 1206, receiving the downloadtransmission by a first wired modem and a second wired modem connectedto the shared signal wired distribution line.

Continuing in FIG. 12, the following optional steps are illustrated: Instep 1208, transmitting upload transmission to the shared signal wireddistribution line according to the determined transmissionsynchronization and bandwidth allocation, by the first wired modem,wherein the upload transmission is a multi carrier signal designed forair interface; And in step 1210, receiving the upload transmission viathe shared signal wired distribution line, by the point to multi pointcentralized synchronizing communication controller designed for airinterface.

In one embodiment, the upload transmission is modulated by OFDMA anduses an amount of sub-channels that is smaller than the entirecomposition of the OFDMA channel.

Referring again to FIG. 12, in one embodiment, the multi carriertransmission is modulated by an OFDM or an OFDMA modulation, and thecentralized synchronizing communication controller comprises a MAC usedby an IEEE 802.16 orthogonal multi carrier modulation. In oneembodiment, the air interface is an IEEE 802.16 orthogonal multi carriermodulation. In one embodiment, the download transmission and the uploadtransmission further comprise payloads. In one embodiment, the sharedsignal wired distribution line is selected from the group of: twistedpair, coax, fiber optics, and a combination thereof.

It is to be understood that the wired medium may be composed of morethan one wired section, such as, but not limited to, a first fiberoptics section converted to a second coaxial section.

The second set of disclosed embodiments relates to a method for creatingan ubiquitous indoor and outdoor wireless communication access cloudfeaturing an embodiment of the hybrid system having multiple hybridconverters acting as a plurality of transmitting/receiving elements.

The ubiquitous indoor and outdoor wireless communication access cloudmay be also referred to as access field.

The access field features a plurality of hybrid converters that aredownlinked wirelessly, and transmit an identical time symbol modulationsignal (simulcasting), so that a transmission ‘field’ from multiplesources is created, enabling any wireless client device to ‘see’ auniform and ubiquitous access channel. The wireless client device mayalso be referred to as ‘user’. The effect is reciprocal in the uplinkdirection. In one embodiment of the invention, the access field isproduced under the above disclosed hybrid system featuring OFDM orOFDMA.

One embodiment of the invention may create a ubiquitous OFDM or OFDMAwireless access field over large indoor and outdoor areas, using aplurality of short-range, thin hybrid converters. The resultant fieldmay extend to the accumulation of all of the hybrid convertersparticipating in the common field group and may be perceived by awireless client as one big coverage zone. Optionally, this embodimentmay enable the creation of at least one large wireless WiMAX accesszone, without the need for a centralized radiating base station.

The second set of disclosed embodiments may enable the creation of atleast one large wireless WiFi access zone, without the need forelaborate frequency planning and complex handover mechanisms betweenmultiple independent WiFi access points, as is the case withconventional WiFi hot zone solutions.

In one embodiment, the access field effect may be used by a CATVoperator that uses a plurality of short-range, thin hybrid converters tocreate large-scale access regions that are suitable for delivery ofmetro level wireless zones.

The access field effect embodiments may introduce one or more of thefollowing aspects:

(a) Many small hybrid converters create one uniform and ubiquitouswideband access cloud.

(b) A wireless client user moving in the generated field does not seemany separate channels, but rather one continuous access channel that isextended over the accumulation of all hybrid converters creating theaccess field.

(c) The plurality of hybrid converters are not interfering with eachother. Instead, they are actually enhancing the accumulated RF fieldstrength at any point in space that is influenced by a number of suchhybrid converters (and similarly for the uplink direction).

Prior art Single Frequency Network (SFN) is a type of radio network thatoperates several transmitters on a single frequency. To avoidinterference, each station is usually run synchronously with the others,using GPS or a signal from a main station or network as a referenceclock. Both radio and television transmissions may be used inconjunction with SFN.

Synchronization of multiple signals can prove to be very difficult,particularly in systems that require high bandwidth. Most attempts atrepeating analog television on the same channel results in “ghosting,”since the repeater creates a second path of information (multipath).However, the conversion to digital television will allow SFNs to be usedreliably for carrying moving images. This is easiest in systems that useOFDM as the transmission mechanism. OFDM uses a large number of very lowbandwidth signals, so it is fairly easy to synchronize multipletransmitters. DVB-T (used in Europe and many other areas) and ISDB-T(used in Japan) both use OFDM and are well-suited for SFN operation.OFDM is also widely used in digital radio systems.

The method of creating an ubiquitous indoor and outdoor access field mayintroduce the following aspects:

(a) Prior art SFN networks need elaborate synchronization mechanisms toallow the plurality of transmitters/receivers to transmit the sameinformation at the exact same time, whereas an embodiment of the systemachieves a natural state of synchronization by utilizing the jointwire-wireless common modulation that spans both the wired and thewireless interface.

(b) Prior art SFN networks are intended for broadcasting (TV, Radioetc.), whereas the embodiments of the system of the present inventionenable general-purpose bi-directional communication networking.

(c) Prior art SFN networks require separate modems for the backhaul andaccess layers, whereas the embodiments of the system of the presentinvention require only a single type of modem and modulation for bothbackhauling and access/distribution.

Moreover, prior art WiFi access points are being used at the corporatelevel to deliver wireless access across many floors and buildings. Theoverall coverage is achieved by deploying multiple access points, whereeach access point covers a small area with a different frequency. Priorart WiFi indeed achieves large area coverage using multiple accesspoints, but the user sees many-access channels when trying to movearound, and therefore is forced to switch channels when moving. Incontrast to prior art, disclosed embodiments of the present inventionfeature an access field effect. The access field effect creates anaccess region spanning many hybrid converters, but still looking likeone continuous channel to the client devices.

The second set of disclosed embodiments is better understood and willbecome apparent to one ordinarily skilled in the art upon examination ofthe following description, which together with the accompanyingdrawings, illustrate the embodiments of the present invention in anon-limiting fashion.

Referring to FIG. 1A and FIG. 2A, illustrating one embodiment of thehybrid system featuring a plurality of hybrid converters, 20 and 21;hybrid converter 20 is located outdoors and hybrid converter 21 islocated in indoors area 1. Another aspect is that almost any arbitraryarrangement of hybrid converters distributed in any outdoor and indoordeployment is possible. Moreover, the hybrid system may even performbetter than a base station located outdoors, in terms of the resultingaccess field generation. To generate the access field of the embodiment,a plurality of hybrid converters 20 and 21 are connected to one wireddistribution line 6, and grouped together in such a way that each of thehybrid converters within the group is down-converting or up-convertingthe identical frequency channel 110 (modulated signal) from thecentralized synchronizing communication controller 7 to identicalwireless RF frequency channel 112 at any given time (which is possiblesince the entire group shares the same wired distribution line 6). It isto be noted that the group of hybrid converters may include all thehybrid converters connected to the wired distribution line 6, or mayinclude only a portion of them; Several groups are possible within thewired distribution line 6; Such groups are referred to as common fieldgroups.

In the case where hybrid converters 20 and 21 form a common field group,resulting wireless orthogonal multi-carrier modulated signals 30 and 32that are generated by hybrid converter 20 are carrying the identicalinformation as wireless orthogonal multi-carrier modulated signals 31and 33 generated by hybrid converter 21. Outdoor wireless client device50 (illustrated in a non-limiting fashion as a phone) is receivingwireless transmissions 30 and 33, because it happens to be in a range ofboth hybrid converter 20 and hybrid converter 21; the combined signal of33 and 30 is produced on the antenna of client device 50, in a way thatthe resulting signal is stronger than what would have been produced ifeither hybrid converter 20 or hybrid converter 21 would have transmittedin different field groups. Similarly, indoor area 1 client device 51 isreceiving the combination of RF signals 31 and 32, because it happens tobe in the range of both hybrid converter 20 and hybrid converter 21.Client device 4 (illustrated in a non-limiting fashion as a laptop),happens to be only in the range of hybrid converter 20, and is thereforereceiving only its signal 30, which is still sufficient to decode thedownlink transmission. In one embodiment, the orthogonal multi-carriermodulated signals are OFDM signals and/or OFDMA signals.

The above description of the downlink transmission to client devices 4,50, and 51 may similarly be applicable to the uplink direction, so thatwhen client device 50 is transmitting, some of its signal 33 is reachinghybrid converter 21 and, at the same time, some of its signal 30 isreaching hybrid converter 20. Both converters may up-convert the samewireless RF channel 113 to the same signal channel 111 that is placed onthe common wired distribution line 6. Both signals may be naturallycombined on wired distribution line 6 at the OFDM or OFDMA level toyield a better and stronger signal for centralized synchronizingcommunication controller 7 to decode.

Reference is now made to the following example, which together with theabove description, illustrates the invention in a non-limiting fashion.In this embodiment, the common field effect is achieved under thefollowing assumptions regarding the multi-carrier modulation, coherencebandwidth, and inter-symbol guard time criteria, as disclosedhereinbelow.

Referring now to the multi-carrier modulation and coherence bandwidthcriteria, in order for the access field effect to occur the modulationhas to be of a multi-carrier (or multi-tone) type, also known in thewireless industry as OFDM (Orthogonal Frequency Division Multiplexing)or OFDMA (Orthogonal Frequency Division Multiple Access). Referring toFIG. 3, in an OFDM or OFDMA modulation, the information is transportedover a multiple number of subcarriers 211 to 212, such that the entiretransmission bandwidth is the sum of all subcarriers in the signal. Whentwo or more hybrid converting sources 20 and 21 are transmitting overthe same bandwidth with the same information, using OFDM or OFDMAmodulation (as is the case in the access field effect), the resultantsignal illustrated in graph 203 is produced on the antenna of clientdevice 50. Subcarrier 215 has a total power resulting from thecorresponding subcarrier 211 transmitted by hybrid converter 20 in thewireless signal 30 plus the corresponding subcarrier 213 transmitted byhybrid converter 21 in wireless signal 33. Subcarrier 215 has a higherpower than what would have resulted if the hybrid converters 20 or 21were to transmit alone. Since the exact amplitudes of the resultingsubcarriers 215 to 216 are dependent on the exact time delay betweensignals 33 and 30, and on the exact location of the specific subcarrierin the frequency domain, the span of all resulting subcarriers may varyfrom very high (constructive interference) to very low (destructiveinterference). It is for this reason that OFDM or OFDMA are used, sothat when considering all subcarriers involved in the transmission, onthe average, the net effect for all subcarriers is a boost in theoverall power received by the client 50.

In the above illustrated embodiment, the net time delay between signals33 and 30 as perceived by client 50 (as a result of both wired mediumpath differences and free space propagation path differences) shouldconform to the following relation:Δt>1/Δf

Where Δf is the coherence bandwidth, referred to as 230. Δf should besmaller than or equal to the total frequency span of subcarriersparticipating in the transmission. For example, in the case of an IEEE802.16 OFDMA (also known as Scalable-OFDMA) channel of 10 MHz thatcontains 1024 subcarriers, the minimal time delay between any two hybridconverters is recommended to be:Δt> 1/10 MhzΔt>0.1 μS

If the delay requirement is translated to the minimal difference inwired infrastructure length between any two hybrid converters, a minimaldistance difference recommendation of about 0.1 μS*1.5e8=15 m isreceived. It is assumed that the propagation velocity of the signal inthe wired medium is about 1.5e8 [m/s]

The above described multi-carrier criterion is relevant for the uplinkcase as well, and the analysis is similar, the only difference beingthat the receiver is located at the side of the centralizedsynchronizing communication controller 7.

Referring now to the inter-symbol guard time criterion, in order for theaccess field effect to occur and to avoid inter-symbol interferencescaused by long delays between signals arriving from/coming to differenthybrid converters, the modulation should be of a type that allows forlong guard periods between consequent symbols. The criterion forinter-symbol guard time can be expressed as follows:Tg>Dmax

Where Dmax is the wired propagation delay of the downlink signal goingbetween the two outermost hybrid converters. In a non-limiting fashion,translated into distance, assuming that the propagation velocity of thesignal in the wired medium is about 1.5e8 [m/s], and assuming that thedimensions of wired distribution line 6 are limited to 1 km, thefollowing is received:Tg>1000 m/1.5e8 [m/s]Tg>7 μS

Therefore, there is a need for a modulation capable of very long guardtimes, such as OFDM or OFDMA. Without limiting the scope of the presentinvention, IEEE 802.16 Scalable-OFDMA can provide guard time of ˜10 μS,which makes it a suitable modulation scheme for creating the accessfield of the present invention.

Referring back to the drawings, FIGS. 13A-13B illustrate embodimentshaving the following steps: In step 1302, determining transmissionsynchronization and bandwidth allocation between a first wireless clientand a second wireless client communicating via a common wirelesscommunication channel, by using a wireless point to multi pointcentralized synchronizing communication controller; In step 1304,transmitting to the air a download multi carrier transmission, via thecommon wireless communication channel using a first wireless frequency,wherein the download multi carrier transmission comprises the determinedtransmission synchronization and bandwidth allocation; In step 1306,receiving the download multi carrier transmission by a first hybridconverter and by a second hybrid converter; In step 1308, shifting thefrequency of the download multi carrier transmission from the firstwireless frequency to a second wireless frequency in the first hybridconverter and in the second hybrid converter; And in step 1310,transmitting the frequency-shifted download multi carrier transmissionto the air from the first hybrid converter and from the second hybridconverter using the second wireless frequency, wherein the transmissioncoverage areas of the first and of the second hybrid converters are atleast partially overlapping, and wherein the first wireless client islocated in the overlapping coverage area.

Continuing 1312 in FIG. 13B, the following optional steps areillustrated: In step 1314, receiving by the first wireless client asuperposition of the frequency-shifted download multi carriertransmissions from the first and from the second hybrid converters; Andin step 1316, transmitting an upload multi carrier transmission to theair, in the second wireless frequency, according to the determinedtransmission synchronization and bandwidth allocation, by the firstwireless client.

Optional steps 1318, 1320, and 1322 illustrate the following: receivingthe upload multi carrier transmission by the first and by the secondhybrid converters; shifting the frequency of the upload transmissionfrom the second wireless frequency to the first common wirelesscommunication channel frequency; and receiving a superposition of thefrequency-shifted received upload multi carrier transmission from thefirst and the second hybrid converters, via the common wirelesscommunication channel, by the wireless point to multi point centralizedsynchronizing communication controller.

Referring again to FIGS. 13A-13B, in one embodiment, the uploadtransmission is modulated by OFDMA and uses an amount of sub-channelsthat is smaller than the entire composition of the OFDMA channel. In oneembodiment, the upload transmission is modulated by OFDMA and uses onesub-channel. In one embodiment, the download transmission and the uploadtransmission further comprise payloads.

Referring again to FIGS. 13A-13B, in one embodiment, the downloadtransmission further comprises a payload. In one embodiment, the multicarrier signal is an OFDM or OFDMA signal and the centralizedsynchronizing communication controller comprises a MAC used by an IEEE802.16 orthogonal multi carrier modulation. In one embodiment, thewireless clients are standard IEEE 802.16 orthogonal multi carriermodulation mobile clients.

Referring back to the drawings, FIGS. 14A-14B illustrate embodimentshaving the following steps: In step 1402, selecting an area to beubiquitously covered by one OFDM or OFDMA communication channel; In step1404, setting at least two hybrid converters having an aggregatedcoverage area that comprises the selected area; In step 1406, connectingthe hybrid converters, via a common communication channel, to a wirelesspoint to multi point centralized synchronizing communication controller,using multi carrier signals having a first frequency; In step 1408,creating a downlink ubiquitous coverage in the selected area bytransmitting from the hybrid converters approximately the same downlinkmulti carrier signals having a second frequency, wherein the secondfrequency downlink signals are at least partially overlapping and aresynchronizing and bandwidth allocating a first and a second wirelessclients; And in step 1410, creating an uplink ubiquitous coverage byusing the at least two hybrid converters for receiving a multi carrieruplink signal transmitted by the first wireless client.

Continuing 1412 in FIG. 14B, the following optional steps areillustrated: In step 1414, receiving by the first wireless client thedownlink multi carrier signals from the first and the second hybridconverters; And in step 1416, transmitting a multi carrier uplink signalto the air, in the second frequency, by the first wireless client.

Optional steps 1418, 1420, and 1422 illustrate the following: receivingthe multi carrier uplink signal by the first and by the second hybridconverters; shifting the frequency of the received multi carrier uplinksignals from the second frequency to the first common communicationchannel frequency; and receiving from the first and the second hybridconverters the superpositioned frequency-shifted received multi carrieruplink signals, via the common communication channel, by the centralizedsynchronizing communication controller.

Referring again to FIGS. 14A-14B, in one embodiment, the multi carrieruplink signals are modulated by OFDMA and use an amount of sub-channelsthat is smaller than the entire composition of the OFDMA channel. In oneembodiment, the multi carrier uplink signals are modulated by OFDMA anduse one sub-channel.

Referring again to FIGS. 14A-14B, in one embodiment, the commoncommunication channel is selected from the group of: twisted pair, coax,fiber optics, and a combination thereof. In one embodiment, the commoncommunication channel is a wireless channel. In one embodiment, thewireless clients are standard IEEE 802.16 orthogonal multi carriermodulation mobile clients.

The third set of disclosed embodiments relates to a method forimplementing multiple downlink channels with a single uplink channelusing a standard that inherently has one uplink channel per eachdownlink channel and a centralized synchronizing communicationcontroller.

In one embodiment, broadcast MAP sections of a downlink transmission ata centralized synchronizing MAC are manipulated so that the clientdevices served by the point-to-multipoint system are “tricked intothinking” that a plurality of symmetrical downlink/uplink channels areat their disposal, when in fact only the multiple downlink channels arephysically in existence, and the at least one uplink physical channelthat exists is being used in all the uplink directions.

For clarity purposes, the terms “centralized synchronizing MAC” and“centralized synchronizing communication controller” may be usedinterchangeably.

In a non-limiting fashion, one embodiment of the invention may beutilized in the case of the hybrid wired-wireless point-to-multipointcommunication system, as disclosed above, when the system operates ontop of a CATV wired infrastructure, where downlink bandwidth is high(for example about 800 Mhz) and uplink bandwidth is limited (for exampleabout 40 Mhz). In this case, the wireless clients may communicate withthe centralized synchronizing communication controller using a standardpoint-to-multipoint protocol such as, but not limited to, the IEEE802.16 as illustrated in the examples below.

The IEEE 802.16 standard is designed to be used in symmetricaluplink/downlink situations (i.e., in cases where for each distinctdownlink physical channel there exists a distinct uplink physicalchannel). The third set of disclosed embodiments manipulates the IEEE802.16 MAC, including the scheduler, at the centralized synchronizingcommunication controller level in such a way that all clients associatedwith the hybrid system use one common (or possibly more than one) uplinkchannels (for example, located in the 40 Mhz uplink band in the case ofCATV) to uplink communication with the centralized synchronizingcommunication controller, but a plurality of downlink channels are usedin the downlink. In this manner, the clients in the hybrid system enjoya large downlink bandwidth that can include many IEEE 802.16 channelsoccupying (potentially) up to the entire available downlink bandwidth(about 800 Mhz in CATV, or the equivalent of 80 10 Mhz IEEE 802.16channels).

Referring to FIG. 4A, wireless point-to-multipoint communication systemsare known for many years; WiMAX (IEEE 802.16) is such a system thatutilizes a frame structure, also referred to as channel, as illustratedby prior art graph 301 in FIG. 4A. Downlink MAP section 302 containsbroadcasted information elements 310 and 320 that are used by the clientdevices to know which part of downlink payload section 304 is intendedfor which client (information element 310 points to payload 311, andinformation element 320 points to payload 321). Similarly, uplink MAPsection 303 contains broadcasted information elements 330 and 340 thatare used by the client devices to know which part of uplink channelsection 305 is reserved for which client (information element 340 pointsto reservation 341, and information element 330 points to reservation331). A standard prior art point-to-multipoint will therefore include adownlink MAP section 302, an uplink MAP section 303, a downlink payloadsection 304, and an uplink payload section 305; all of which beingtransmitted over one channel (and one frequency, in the case of a TDDsystems).

The disclosed embodiments are useful in systems having the need fordownlink transmission of a very large bandwidth (such as video on demandcontent), in which a very large downlink bandwidth is needed but only amoderate bandwidth uplink return channel is necessary and/or available.An example for such a system is the CATV.

Alternatively phrasing, in the case of CATV, signals are transmitted onthe coax line at various frequencies according to the number ofchannels. When the signal reaches the end-point station, everytransmitter converts the signal to an appropriate wireless signal. In anembodiment of the invention, the system is a TDD system wherein theclient responds at the same frequency. In order to prevent collisionsbetween different clients that are trying to transmit using the samefrequency at the same time, all clients share the same uplink MAP. Allhybrid converters convert their uplink data to the same uplinkfrequency, i.e. all hybrid converters transmit using the same uplinkchannel (in the case where there is only one uplink channel). Thecentralized synchronizing communication controller is able to assigneach frame of received-uplink-data to its corresponding clients by usingthe uplink MAP. It is to be understood that all clients share both timeand subcarriers.

In one embodiment of the invention, the system is an FDD system whereinthe downlink uses a different frequency than the uplink.

Graphs 401 and 402 in FIG. 4B are schematic illustrations of thecombined frame structure of multiple downlink channels with a singleuplink channel as intended to be used in possible embodiments. Graphs401 and 402 illustrate two downlink channels, and one uplink channel,but it is to be understood that the present invention can be generalizedto M downlink channels over N uplink channels, where N≦M (the standardknown case is N=M). For explanatory purposes only, FIG. 4B illustratesthe case of two downlink channels.

In the illustrated example, the centralized synchronizing communicationcontroller 7 generates two (but is not limited to two) downlink channelsextending in time over 302, 303, and 304, one is shown in graph 401 andthe other in graph 402; the downlink channels are transmitted on twoseparate frequencies over the wired distribution line 6. The firstdownlink channel, illustrated in graph 401, is converted by the hybridconverter 21 from the wired distribution line 6 to the wireless channelfrequency 33, so that only client 50 is served by this channel (forsimplicity it is assumed that each downlink channel serves only oneclient, but the case can be extended to any number of clients per accesschannel), and client 50 decodes transmission element 410 to understandthat payload 411 is intended for it. Similarly, the second downlinkchannel, illustrated by graph 402, is converted by the hybrid converter20 from the wired distribution line 6 to the wireless channel frequency30, so that only client 4 is served by this channel, and it decodes thetransmission element 420 to understand that the payload 421 is intendedfor it.

According to this embodiment, both graphs 401 and 402 have the exactsame uplink MAP, so that transmission elements 430 and 440 areduplicated, such that they appear on the uplink MAP of both downlinkchannels. This means that the uplink channel is shared by both clients 4and 50. Since client 4 is transmitting its uplink data 431 (pointed toby transmission element 430) on wireless channel 30, which is differentfrom wireless channel 33 transmitted by client 50 with data 441 (pointedto by transmission element 440), it is up to hybrid converters 20 and 21to place wireless signals 30 and 33 (carrying uplink payloads 431 and441) on the same wired uplink channel, so that centralized synchronizingcommunication controller 7 receives uplink payloads 431 and 441 onuplink wired channel 305.

Similarly to FIGS. 4A and 4B, FIGS. 4C and 4D illustrate FDD channelscomprising multiple downlink channels and a single uplink channel. Graph401 is the first downlink channel having a second frequency, graph 402is the second downlink channel having a third frequency, andillustration 403 is the first uplink channel having a first frequency.Illustration 403 is the combined uplink channels of 401 and 402.

The hybrid converter transmits to the air one downlink channel selectedfrom the downlink channels that are transmitted over the shared signalwired distribution line. Selecting the downlink channel to betransmitted to the air may be achieved by any appropriate hybridconverter embodiment, such as, but not limited to: a hybrid converterwith a predetermined channel, hybrid converter with a pre-set channel,and/or a hybrid converter with a channel selector.

The above-described third set of disclosed embodiments is capable oftransmitting multiple downlink channels with at least one return uplinkchannel to standard 802.16 OFDM or OFDMA clients. This method is usefulin hybrid system situations where downlink bandwidth is high, and uplinkbandwidth is low, like in the case of CATV wired infrastructure.

It is to be understood that the third set of disclosed embodiments canbe extended to at least one uplink channel with multiple downlinkchannels, provided that there are more downlink channels than uplinkchannels. This is advantageous for each shared media and for eachnetwork where everyone receives from everyone. FDD is a common mediumsystem of multiple downlink channels sharing a single uplink channel.

Referring back to the drawings, FIG. 15 illustrates a method forcommunicating with a first and a second wireless client having thefollowing steps: In step 1502, centrally allocating bandwidth to, andsynchronizing communications with a first and a second wireless client;In step 1504, transmitting, over a shared signal wired distributionline, a first downlink signal transported over a first frequency, asecond downlink signal transported over a second frequency, and anuplink signal transported over a fifth frequency; In step 1506,converting the frequency of the first downlink signal to a thirdfrequency, and bi-directionally wirelessly communicating with a firstwireless client over the third frequency; In step 1508, converting thefrequency of the second downlink signal to a fourth frequency, andbi-directionally wirelessly communicating with a second wireless clientover the fourth frequency; And in step 1510, converting andsuperpositioning a first received wireless uplink signal having thethird frequency and a second received wireless uplink signal having thefourth frequency to the uplink signal that is transmitted over theshared signal wired distribution line using the fifth frequency.

Referring again to FIG. 15, in one embodiment, the step of convertingand superpositioning the first and the second received wireless uplinksignals to the uplink signal having the fifth frequency is performed byusing a first and a second hybrid converter, respectively. In oneembodiment, the uplink signal is a combined signal resulting from asuperpositioning of the fifth frequency signal coming from the firsthybrid converter, and the fifth frequency signal coming from the secondhybrid converter.

Referring again to FIG. 15, one embodiment further features the optionalsteps of: converting the first frequency of the first downlink signal tothe third frequency by using the first hybrid converter; and convertingthe second frequency of the second downlink signal to the fourthfrequency by using the second hybrid converter.

Referring again to FIG. 15, in one embodiment, the first and the secondhybrid converters have at least partially overlapping coverage areas andthe first wireless client is located in the overlapping coverage area.

Referring again to FIG. 15, in one embodiment, the signals are OFDM orOFDMA signals. In one embodiment, the step of centrally allocatingbandwidth and synchronizing communications comprises the use of a MACused by an IEEE 802.16 orthogonal multi carrier modulation. In oneembodiment, the wireless clients are standard IEEE 802.16 orthogonalmulti carrier modulation mobile clients. In one embodiment, the firstreceived wireless uplink signal and the second received wireless uplinksignal are modulated by OFDMA and each of the signals uses an amount ofsub-channels that is smaller than the entire composition of the OFDMAchannel. In one embodiment, the first received wireless uplink signaland the second received wireless uplink signal are modulated by OFDMAand each of the signals uses one sub-channel.

The fourth set of disclosed embodiments relates to a filtering processto enhance uplink reception sensitivity in OFDMA hybrid wired-wirelesspoint to multipoint communication systems.

The fourth set of disclosed embodiments is better understood and willbecome apparent to one ordinarily skilled in the art upon examination ofthe following description, which together with the accompanyingdrawings, illustrate the present invention in a non-limiting fashion.

The disclosed uplink OFDMA filtering process may resolve the thermalnoise buildup problem in the uplink channel of hybrid wired-wirelesspoint to multipoint communication systems. The thermal noise buildupproblem is caused by the simultaneous transmission of multiple hybridconverters in uplink direction 111.

For example, in a 10 Mhz channelization IEEE 802.16e transmission, eachconverter adds its 10 Mhz thermal noise to the overall noise picked bythe receiver of centralized synchronizing communication controller 7, sothat the total sensitivity of centralized synchronizing communicationcontroller 7 is degraded by the amount of:10*log [Number of hybrid Converters per uplink channel] dB

This effect may cause the downlink and uplink directions to beasymmetrical in terms of sensitivity, which is usually unwanted. Theembodiment of the hybrid system, and other communication systems, aredesigned to support bi-directional communication and therefore shouldhave symmetrical sensitivity.

The filtering process is useful for the OFDMA uplink channel, wheremultiple users transmit simultaneously on the same uplink channel byusing different sub-carrier groups within the channel. Each group isallocated on a symbol-by-symbol basis to a specific user (thesub-carrier groups are also called sub-channels).

In one embodiment, the filter is placed at the hybrid convertertransmission side, and is basically blocking the non-active sub-carriers(i.e., the carriers that carry only thermal noise with no signal), sothat only information-carrying sub-carriers are relayed up to thecentralized synchronizing communication controller. The result is thatno excess thermal noise builds up at the centralized synchronizingcommunication controller receiver side.

In one embodiment, each hybrid converter has its own wired distributionline, as illustrated in FIG. 1C. In this case, the filters may be placedin a central location, for example before the superposition of thesignals at 6 b.

Since in most OFDMA wireless standards (such as the IEEE 802.16e PUSCmode), the sub-carriers are pseudo-randomly distributed across thechannel (for spectral diversity purposes), the blocking ofnon-information carrying sub-carriers within the uplink channel requiresa filtering that is performed at the individual sub-carrier level, andthis is what the disclosed filtering process does.

Alternatively phrasing, when there are many hybrid converters that canperform up and down frequency conversion without having the ability toupload only real data, the centralized synchronizing communicationcontroller may receive a signal that features a low SNR, due to the factthat the noise from the multiple hybrid converters may be summed up to asignificant noise. In one embodiment of the present invention, thehybrid converters include a filter and therefore are able to filter outthe thermal noise. The following two non-limiting examples enable thehybrid converter to filter out the noise:

(a) The hybrid converter performs an FFT and, if the result per carrieris bigger than a predefined threshold, the received signal is uploaded.Otherwise, the received signal is filtered out.

(b) all the sub-carriers that belong to the same sub-channel of aspecific packet are taken and it is checked whether the sum of allsub-channels passes a predefined threshold or not. If the sum of allsub-channels passes a predefined threshold, the data is uploaded fromall the sub-channels that belong to the user. Otherwise, all thesub-channels are filtered out, even if there are a few sub-channelswhich are stronger than the threshold.

In another embodiment of the invention, it is not necessary to know withwhich client the system is communicating because the groups ofsub-channels are known and defined in the protocol. In the case wherethere are a number of possible combinations of the sub-channels, allpossibilities are checked and those that pass the threshold aretransmitted.

FIG. 6 is a schematic block diagram illustrating the sub-carrier levelfiltering process, which may be performed at the hybrid converter uplinktransmission path. The filter may be located before Band Pass Filter(BPF) 501 as an example. The signal from hybrid converter antenna 600 isdown converted to Baseband (BB), and sampled by A/D 601 to be processedby an FFT block 602. Optionally, the FFT size is in accordance to thenumber of sub-carriers supported by the OFDMA uplink channel, so thateach bin of FFT block 602 output represents a sub-carrier in the uplinkOFDMA channel. The resultant FFT bins are sent to a sub-carriersuppressor block 603 (on a per time symbol basis), where they areprocessed to determine which bins (sub-carriers) will be relayed to thecentralized synchronizing communication controller 7 (carryinginformation), and which bins are blocked (carrying thermal noise and noinformation). The bins that carry information are sent to IFFT block 604for reconstruction of the time domain uplink channel, and are convertedback to analog form by D/A 605. The resulting reconstructed signal 606is passed on for uplink transmission.

Suppressor block 603 may employ one of the following blocking algorithmsas a non-limiting example (and without limiting the generality of thedisclosed sub-carrier level filtering process): (a) Define apredetermined power level threshold, and block each sub-carrier that isbelow the predetermined power level. (b) Integrate the power of eachsub-carrier group (sub-channel), and block entire groups if theintegrated power is below the predetermined power level.

It is to be noted that the disclosed uplink filtering process wasdescribed in the context of the hybrid communication system of thepresent invention, but can be similarly employed in uplink OFDMAnon-regenerative wireless-to-wireless relays, or in any other uplinksystem in which multiple OFDMA relays (converters) are being used inparallel on the same uplink channel.

The above-described fourth set of disclosed embodiments is capable ofcreating a filtering process for any communication system that employsmultiple uplink relays, also referred to as converters, that operateover a common uplink OFDMA channel. The disclosed filtering processsolves the uplink thermal noise buildup associated with uplink channelof such systems, so that the reception sensitivity of the centralizedsynchronizing communication controller is kept at its theoretical level,regardless of the number of deployed relays.

For example, the disclosed filtering process may be used with OFDMA IEEE802.16e (WiMAX) hybrid communication systems that are working in asimulcast mode, where many hybrid converters share the same uplinkchannel.

Referring back to the drawings, FIG. 16A illustrates embodiments havingthe following steps: In step 1602, determining transmissionsynchronization and bandwidth allocation for a plurality of wirelessclients; In step 1604, communicating with the wireless clients via aplurality of hybrid converters connected to a shared signal distributionline, by using a wireless point to multi point centralized synchronizingcommunication controller and an OFDMA modulation; In step 1606,receiving wireless upload transmission by using the hybrid converters;And in step 1608, blocking non-information carrying sub-carriers,received by at least one of the hybrid converters, beforesuperpositioning the received wireless upload transmissions on theshared signal distribution line.

Referring again to FIG. 16A, in one embodiment, the shared signaldistribution line is a shared signal wired distribution line, and thehybrid converters are shifting the frequency of the received uploadtransmissions from a wireless frequency to a wired communication linefrequency. In one embodiment, the shared signal wired distribution lineis selected from the group of: twisted pair, coax, fiber optics, and acombination thereof.

Referring again to FIG. 16A, in one embodiment, the shared signaldistribution line is a shared signal wireless distribution line and thehybrid converters are shifting the frequency of the received uploadtransmissions from a first wireless frequency to a second wirelessfrequency. In one embodiment, the wireless clients are standard IEEE802.16 orthogonal multi carrier modulation mobile clients. In oneembodiment, the wireless point to multi point centralized synchronizingcommunication controller comprises a MAC used by an IEEE 802.16orthogonal multi carrier modulation. In one embodiment, the uploadtransmission uses an amount of sub-channels that is smaller than theentire composition of the OFDMA channel. In one embodiment, the uploadtransmission uses one sub-channel.

Referring back to the drawings, FIGS. 16B-16C illustrate two examples ofimplementing step 1608 of blocking non-information carryingsub-carriers.

In FIG. 16B, the following steps are illustrated: In step 1610,performing an FFT; In step 1612, suppressing signals below a predefinedthreshold according to a per-carrier examination; And in step 1614,performing an IFFT.

In FIG. 16C, the following steps are illustrated: In step 1610,performing an FFT; In step 1616, suppressing sub-channels that do notbelong to a predefined user according to sub-channel examination; Instep 1618, suppressing sub-channels that do not pass a predefinedthreshold according to sub-channel examination; And in step 1614,performing an IFFT.

Referring again to FIG. 16A, in one embodiment, at least two of thehybrid converters have at least partially overlapping coverage areas andat least one wireless client is located in the overlapping coveragearea.

One embodiment further comprises the steps of receiving by the at leastone wireless client a superposition of transmissions from the at leasttwo hybrid converters; and transmitting an upload transmission to theair by the wireless client.

The fifth set of disclosed embodiments relates to a method ofsimultaneous transmitting of simulcast and single cast information overa single point to multipoint communication channel created by anembodiment of the hybrid system of the present invention.

The formed wireless access fields may feature different dimensionsand/or contain other wireless access fields. The embodiments enablechanging the wireless access field dimensions in a dynamic manner. Byusing the disclosed hybrid converters, it is possible to createvirtually any required wireless access fields division. Moreover, if awireless access field within another wireless access field is desired,then the same hybrid converter may transmit in at least two differentfrequencies.

A simultaneous transmitting of simulcast and single cast informationover a single point to multipoint communication channel uses a singlepoint to multipoint channel in such a way that a common access fieldcloud (as described above, also known as simulcasting) is formed over agroup of hybrid converters, but at the same time the same point tomultipoint channel is also used to enable each of the hybrid convertersin the simulcast group (or sub-groups within the group) to supportsingle casting operation (meaning that each converter transmits/receivesinformation that is not shared with the rest of the group).

Moreover, the disclosed simultaneous simulcasting/single casting over ashared channel, enables the hybrid communication system of the presentinvention, or other hybrid communication systems, to use the sametransmission/reception hardware to do both simulcasting and singlecasting.

Referring to FIG. 9A, each small wireless access field 900, 901, 902,903, represents a different access field sub-grouping, which all hybridconverters transmit, in addition, in the frequency, or time domain, ofthe larger wireless access field 910. Optionally, mobile userscommunicate with large access field 910 and the stationary users, whichneed a wide bandwidth, communicate with the appropriate frequencies, ortime domains, in the smaller wireless access fields 900, 901, 902, 903.

It is to be understood that the meaning of implementing STC with thedisclosure of the present invention results in dividing the stationsbetween the two scrambled series.

In the case where there is a large access field and it is desired todivide it into several smaller access fields, an embodiment of thepresent invention introduces the benefit of no need to add hybridconverters. It is only necessary to add the appropriate MAC and RFfront-end in the centralized synchronizing communication controller.

Herein disclosed are several examples of methods for dividing the accessfields by using the hybrid converters which are available in the area,and the required changes on the centralized synchronizing communicationcontroller:

(a) the number of up and down converting elements is multiplied by thenumber of access fields to be created. In this case, the centralizedsynchronizing communication controller transmits one common channel anda few private channels, therefore if there are ‘n’ private channels, thecentralized synchronizing communication controller should have (n+1) PHYand MAC elements. This option is simple to implement from an engineeringstandpoint.

(b) the number of units (each featuring an up-converter, adown-converter and an antenna), at each hybrid converter, is increased.Using that configuration, in order to add an additional channel, anadditional unit is added. In this case, for TDD there is a need tosynchronize the different access fields. This may be done by adding aMAC & PHY for each channel and synchronizing the different channels byusing the appropriate software in the centralized synchronizingcommunication controller, wherein the software schedules when the relayis in which access field.

(c) using TDD and an up converter that moves fast between the differentintermediate frequencies (IFs). The up converter is synchronized withthe frequency of the channel that has to be transmitted. In this case, a“Super MAC” is used for synchronizing the different MACs to have acommon channel. This is done at the scheduler level that coordinates theinsertion of the common channel among the different channels.

(d) using sub-channels for creating both common access zones and privateaccess zones, using one channel. In OFDMA there are sub-channels and theextraction of the sub-channel is part of the standard.

In one embodiment, in order to ensure that the SFN access field iscreated at the same time, the common channels of all of the contributorsare located in the same sub-channel and on the same time. It should benoted that using the SFN reduces the bandwidth that is allocated to eachapplication. As a result, this method is particularly applicable toapplications that do not require a wide bandwidth. The percent of thebandwidth allocated to each application depends on the applicationattributes, requirements, and desired objectives.

The IEEE 802.16 standard defines time-frames for transmitting the MAP(i.e. who transmits, who receives, and when). In one embodiment, the MAPis a means for synchronization. The MAP may be implemented by abroadcast to which all users listen. According to one embodiment, it isadvantageous to transmit the MAP in a manner that all pointers that arepointing to common areas are in the same location in the MAP. Therefore,it does not matter from where a MAP is being received; it is alwayspossible to synchronize on the common area. In the case when pointersare pointing to exclusive areas, every access field has differentinformation for each sub-access field.

The fifth set of disclosed embodiments is better understood and willbecome apparent to one ordinarily skilled in the art upon examination ofthe following two methods for transmitting simulcast and single castinformation simultaneously over a single point to multipoint channel, asdisclosed hereinbelow, which together with the description andaccompanying drawings, illustrate the embodiments of the presentinvention in a non-limiting fashion. The first method utilizes OFDMAsub-channelization, and the second method utilizes OFDM/OFDMA timedivision.

Reference is now made to the following method for transmitting simulcastand single cast information simultaneously over a single point tomultipoint channel by utilizing OFDMA sub-channelization.

FIG. 7 is a schematic illustration of combining simulcast and singlecast in the same OFDMA channel by the utilization of sub-channelization.Channel 710 is transmitted to and/or received from one transmitter (thetransmitter may be, but is not limited to, a hybrid converter 20 forexample), and channel 711 is transmitted to and/or received from asecond transmitter (the transmitter may be, but is not limited to, ahybrid converter 21 for example). It is to be understood that theexample is not limited to two transmitting/receiving elements 20, 21,and can be similarly used for any number of such elements. MAP regions700 and 701 of both channels 710 and 711 include identical informationelements 720, 721, 722, 730, 731, 732, that act as pointers fortransmission/reception scheduling of the wireless clients, but onlydownlink payload 740 (that is pointed to by information element 720) isshared by both channels 710 and 711 (and therefore transmitted from bothconverters 20 and 21 in this example), whereas downlink payload 741(pointed to by information element 721) is transmitted only with channel710 (and therefore only by converter 20 in this example) and downlinkpayload 742 (pointed to by information element 722) is transmitted onlywith channel 711 (and therefore only by converter 21 in this example).Since payload 740 is shared by both converters 20 and 21, and itoccupies the identical sub-channels in both of the point to multipointOFDMA channels 710 and 711, it is effectively being simulcasted. Sincepayload 741 is transmitted only by the converter 20, it will be pickedby users that are in close proximity to that converter only, andsimilarly payload 742 is transmitted only by converter 21, and will bepicked by users that are in close proximity to that converter only.Payloads 741 and 742 are transmitted over the same spectrum (the samesub-channels within the main channel frequency), but are receivedseparately by, for example, client 4 and client 50, since 4 is close to20 and 50 is close to 21. Both clients 4 and 50 are able to decodepayload 740, since it is simulcasted.

As seen, the separation between information that is simulcast andinformation that is single cast may be done at the frequency sub-channellevel, which is a feature of point to multipoint OFDMA systems. The sametechnique may also be used in the uplink direction, so that the uplinkpayload 750 (pointed to by the information element 730) is received, forexample, by the centralized synchronizing communication controller 7from both converters 20 and 21, whereas payloads 751 and 752 (pointed toby information elements 731 and 732 respectively) are receivedseparately from converters 20 and 21 (respectively), and containdifferent information.

It is noted that in the above example, two chunks of sub-channels areused, but any number of sub-channel separations may be used, as isindeed possible by communication techniques like, but not limited to,IEEE 802.16e OFDMA.

Reference is now made to the following method for transmitting simulcastand single cast information simultaneously over a single point tomultipoint channel by utilizing OFDM and/or OFDMA time division.

FIG. 8 is a schematic illustration of combining simulcast and singlecast in the same OFDM/OFDMA channel by the utilization of time division.Channel 810 is transmitted to and/or received from a first transmitter(the transmitter may be, but is not limited to, a hybrid converter 20,for example), and channel 811 is transmitted to and/or received from asecond transmitter (the transmitter may be, but is not limited to, ahybrid converter 21, for example). It is noted that the example is notlimited to two transmitting and/or receiving elements 20 and 21, and canbe similarly used for any number of such elements. MAP regions 800 and801 of both channels 810 and 811 include identical information elements820, 821, 822, 830, 831, and 832 that act as pointers fortransmission/reception scheduling of the wireless clients, but onlydownlink payload 840 (that is pointed to by information element 820) isshared by both channels 810 and 811 (and therefore transmitted from bothconverters 20 and 21 in this example), whereas downlink payload 841(pointed to by information element 821) is transmitted only with channel810 (and therefore only by converter 20 in this example) and downlinkpayload 842 (pointed to by information element 822) is transmitted onlywith channel 811 (and therefore only by converter 21 in this example).Since payload 840 is shared by both converters 20 and 21, and occupiesidentical time tags in both of the point to multipoint OFDM or OFDMAchannels 810 and 811, it is effectively being simulcasted. Since payload841 is transmitted only by converter 20, it will be picked by users thatare in close proximity to that converter, and similarly payload 842 istransmitted only by converter 21, and will be picked by users that arein close proximity to that converter. Payloads 841 and 842 aretransmitted over the same time (the same time symbols within the mainchannel), but are received separately by, for example, client 4 andclient 50, since 4 is close to 20 and 50 is close to 21. Both clients 4and 50 are able to decode payload 840, since it is simulcasted.

As seen, the separation between information that is simulcast andinformation that is single cast may be done at the time division level.The same technique may also be used in the uplink direction, so that theuplink payload 850 (pointed to by the information element 830) isreceived by the centralized synchronizing communication controller 7 (asa non-limiting example) from both converters 20 and 21, whereas payloads851 and 852 (pointed to by information elements 831 and 832respectively) are received separately from converters 20 and 21(respectively), and contain different information.

It is to be noted that in the above example, two chunks of time-symbolsare used as an example, but any number of time-symbol separations may beused—as is indeed possible by communication techniques such as, but notlimited to, IEEE 802.16e, or IEEE 802.11. Moreover, it is to beunderstood that above described features of the invention, which are,for clarity, described in the context of separate embodiments, may alsobe provided in various combinations in a single embodiment. For example,a combination of sub-channelization and time division separation betweensimulcasting and single casting over the same OFDMA channel may beemployed.

The above-described fifth set of disclosed embodiments is capable ofcombining both simulcasting and single casting information over the samepoint to multipoint channel and using multiple Tx/Rx sources. Thedisclosed embodiments allow using the same hardware elements to deliverboth a ubiquitous coverage cloud over the sum of all covered areas byall Tx/Rx sources, and dedicated per Tx/Rx source information, thatallow using high bandwidth transmissions and using very efficientfrequency reuse factors.

Moreover, it is to be noted that the fifth set of disclosed embodimentsis very well suited for usage with the hybrid point to multipointcommunication systems, as described above in the first and the secondsets of disclosed embodiments.

An example of where simulcast/single cast separation over one channelmay be used is in systems where both a large area of continuous coverageis needed (for example, for mobile voice applications), and at the sametime a very local and high bandwidth is needed for nomadic clients (forexample, streaming to laptops). Without limiting the scope of theinvention, in one embodiment of the invention, WiMAX IEEE 802.16e may beused for implementing the disclosed method of the present invention.

The private channels' coverage areas are characterized by the fact thata private signal having a first coverage area does not interfere with asecond private signal having a second coverage area.

a client that is in close proximity to a converter may be assigned to aprivate channel or to the common channel. A client that is not in one ofthe private channels may be assigned only to the common channel.

Assigning the clients to the common or to the private channels may beperformed dynamically and/or a-priori in a static manner. For example, aclient may be manually located and assigned to a private or commonchannel. Alternatively, the centralized synchronizing communicationcontroller may scan the available private channels in order to map theclients and determine the possible channel assignments.

FIG. 9B illustrates three hybrid converters 951, 952, and 953; Eachhybrid converter features a private coverage area, referred to as 941,942 and 943 correspondingly. The communication system features a commoncoverage area 930. Wireless client 969 is able to communicate over thecommon channel 930 while wireless client 962 is able to communicateeither over the common channel 930 or over private channel 942.

Referring back to the drawings, FIGS. 17A-17C illustrate embodimentshaving the following steps: In step 1702, selecting an area to beubiquitously covered by a common channel; In step 1704, assigning afirst wireless client to the common channel; In step 1706, assigning asecond wireless client to a first private channel; In step 1708, settinga first hybrid converter and a second hybrid converter having anaggregated coverage area that comprises the selected area; In step 1710,connecting the first hybrid converter using an orthogonal multi-carriertransmission having a first frequency and the second hybrid converterusing an orthogonal multi-carrier transmission having a second frequencyto a centralized synchronizing communication controller via a sharedsignal wired distribution line; In step 1712, converting, by using thefirst hybrid converter, the first frequency transmission to a thirdorthogonal multi-carrier wireless transmission having a third frequency;In step 1714, converting, by using the second hybrid converter, thesecond frequency transmission to a fourth orthogonal multi-carrierwireless transmission having the third frequency; And in step 1716,creating a downlink ubiquitous coverage in the selected area bytransmitting the third and the fourth transmissions, each comprising acommon MAP over a first sub-channel, a common payload over a secondsub-channel, and a first private payload and a second private payload,correspondingly, over a third sub-channel, wherein the third and fourthtransmissions are at least partially coverage-overlapping and aresynchronizing and bandwidth allocating a first wireless client and asecond wireless client.

Continuing 1720 in FIG. 17B, the following optional steps areillustrated: In step 1722, receiving, by the first wireless client, thethird and the fourth transmissions from the first and the second hybridconverters; And in step 1724, transmitting an uplink to the air, usingthe third frequency, and according to the received synchronization andbandwidth allocation, by the first wireless client.

Referring again to FIGS. 17A-17B, one embodiment further comprisesmodulating the uplink by OFDMA and using an amount of sub-channels thatis smaller than the entire composition of the OFDMA channel. Oneembodiment further comprises modulating the uplink by OFDMA and usingone sub-channel.

Continuing 1012 in FIG. 17C, the following optional steps areillustrated: In step 1726, creating an uplink ubiquitous coverage byusing the first hybrid converter for receiving a multi carrier uplinkwireless signal transmitted by the first wireless client; and in step1728, converting the signal received from the first wireless client, bythe first hybrid converter, to a first uplink signal having the firstfrequency for communicating with the centralized synchronizingcommunication controller via the shared signal wired distribution line.

Continuing in FIG. 17C, the following optional steps are illustrated: Instep 1730, creating an uplink private channel by using the second hybridconverter for receiving a multi carrier uplink wireless signaltransmitted by the second wireless client; And in step 1732, convertingthe signal received from the second wireless client, by the secondhybrid converter, to a second uplink signal having the second frequencyfor communicating with the centralized synchronizing communicationcontroller via the shared signal wired distribution line.

Continuing in FIG. 17C, the following optional steps are illustrated: Instep 1734, using a third hybrid converter for receiving a multi carrieruplink wireless signal transmitted by a third wireless client; In step1736, converting the signal received from the third wireless client, bythe third hybrid converter, to a third upload signal having the firstfrequency for communicating with the centralized synchronizingcommunication controller via the shared signal wired distribution line;And in step 1738, superpositioning the sub-carriers of the commonpayloads of the first and the third uplink signals.

Referring again to FIG. 17C, in one embodiment, the step ofsuperpositioning the sub-carriers is performed by using the centralizedsynchronizing communication controller.

Referring again to FIG. 17A, in one embodiment, the shared signal wireddistribution line is selected from the group of: twisted pair, coax,fiber optics, and a combination thereof. In one embodiment, theorthogonal multi-carrier transmissions are OFDM or OFDMA transmissions.In one embodiment, the centralized synchronizing communicationcontroller further comprises a MAC used by an IEEE 802.16 orthogonalmulti carrier modulation. In one embodiment, the wireless clients arestandard IEEE 802.16 orthogonal multi carrier modulation mobile clients.

Referring back to the drawings, FIGS. 18A-18E illustrate a method forcommunicating with a first and a second wireless clients via a point tomultipoint shared signal wired distribution line having the followingsteps: In step 1802, transmitting to a first hybrid converter a firsttransmission having a first frequency; transmitting to a second hybridconverter a second transmission having a second frequency, wherein thefirst transmission and the second transmission are orthogonalmulti-carrier modulation signals comprising a common MAP over a firstsub-channel, a common payload over a second sub-channel; and the firsttransmission further comprising a first private payload and the secondtransmission further comprising a second private payload,correspondingly, over a third sub-channel; In step 1804, converting, byusing the first hybrid converter, the first transmission to a thirdwireless transmission having a third frequency; In step 1806,converting, by using the second hybrid converter, the secondtransmission to a fourth wireless transmission having the thirdfrequency; And in step 1808, wirelessly transmitting the thirdtransmission and the fourth transmission for communicating with thefirst and the second wireless clients.

Continuing 1810 in FIG. 18B, the following optional steps areillustrated: In step 1812, the first wireless client communicates withthe first hybrid converter using the third frequency, wherein the firstwireless client uses the common payload; And in step 1814, the secondwireless client communicates with the second hybrid converter using thethird frequency, wherein the second wireless client uses the secondprivate payload.

Referring again to FIG. 18A, one embodiment further comprises the stepof the first wireless client communicating with the first hybridconverter using the third frequency, wherein the first wireless clientuses the first private payload; and the second wireless clientcommunicating with the second hybrid converter using the thirdfrequency, wherein the second wireless client uses the second privatepayload.

Referring again to FIG. 18A, in one embodiment, the first and the secondwireless clients are standard IEEE 802.16 orthogonal multi carriermodulation clients. In one embodiment, the first, second and thirdsub-channels are standard IEEE 802.16 orthogonal multi carriermodulation sub-channels. In one embodiment, the shared signal wireddistribution line is selected from the group of: twisted pair, coax,fiber optics, and a combination thereof. In one embodiment, theorthogonal multi-carrier modulation signals are OFDM or OFDMA signals.

Continuing 1810 in FIG. 18C, the following optional steps areillustrated: In step 1816, receiving a first uplink transmission fromthe first wireless client by using the first hybrid converter; receivinga second uplink transmission from the second wireless client by usingthe second hybrid converter; wherein the first and the second uplinktransmissions are transmitted over the third frequency; In step 1818,converting the first uplink transmission to a third uplink transmissionhaving the first frequency and converting the second uplink transmissionto a fourth uplink transmission having the second frequency; In step1820, transmitting the third and the fourth uplink transmissions overthe shared signal wired distribution line; In step 1822,superpositioning the sub-carriers of the common payloads of the firstand the second uplink transmissions; And in step 1824, decoding thesuperpositioned transmission.

Referring again to FIG. 18C, in one embodiment, the superpositioning isperformed by using a centralized synchronizing communication controller.

Continuing 1810 in FIG. 18D, the following optional steps areillustrated: In step 1826, receiving a first uplink transmission byusing the first hybrid converter; receiving a second uplink transmissionby using the second hybrid converter; wherein the first and the seconduplink transmissions are transmitted over the third frequency; In steps1828 and 1830, converting the first uplink transmission to a thirduplink transmission having a fourth frequency and converting the seconduplink transmission to a fourth uplink transmission having the fourthfrequency; And

in step 1832, transmitting the third and the fourth uplink transmissionsover the shared signal wired distribution line.

Referring again to FIG. 18C, in one embodiment, the fourth frequency isthe first frequency or the second frequency. One embodiment furthercomprises the step of decoding the superpositioned uplink transmissionby using a centralized synchronizing communication controller.

Continuing 1810 in FIG. 18E, the following optional steps areillustrated: In step 1834, receiving a first uplink transmission fromthe first wireless client by using the first hybrid converter; receivinga second uplink transmission from the second wireless client by usingthe second hybrid converter; wherein the first and the second uplinktransmissions are transmitted over the third frequency and eachcomprises a private payload; In steps 1836 and 1838, converting thefirst uplink transmission to a third uplink transmission having thefirst frequency and converting the second uplink transmission to afourth uplink transmission having the second frequency; In step 1840,transmitting the third and the fourth uplink transmission over theshared signal wired distribution line; And in step 1842, decoding thesub-carrier of the private payload of the third uplink transmission anddecoding the sub-carrier of the private payload of the fourth uplinktransmission.

Referring again to FIG. 18C, in one embodiment, the decoding of thesub-carrier of the private payloads is performed by using a centralizedsynchronizing communication controller.

Thus, it is understood from the embodiments of the invention hereindescribed and illustrated above, that the methods and systems of thepresent invention are neither anticipated or obviously derived from theprior art.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable sub-combination.

It is to be understood that the present invention is not limited in itsapplication to the details of the order or sequence of steps ofoperation or implementation of the disclosed method or to the details ofconstruction, arrangement, and, composition of the corresponding systemthereof, set in the description, drawings, or examples of the presentinvention.

The disclosed embodiments may be implemented with broadbandcommunication standards such as WiFi and WiMAX standards, but it is tobe understood that the present invention is highly useful for othercommunication standards as well.

Citation or identification of any reference in this application shallnot be construed as an admission that such reference is available asprior art to the present invention.

While the invention has been described in conjunction with specificembodiments and examples thereof, it is to be understood that they havebeen presented by way of example, and not limitation. Moreover, it isevident that many alternatives, modifications and variations will beapparent to those skilled in the art. Accordingly, it is intended toembrace all such alternatives, modifications and variations that fallwithin the spirit and broad scope of the present invention.

Any element in a claim that does not explicitly state “means for”performing a specific function, or “step for” performing a specificfunction, is not to be interpreted as a “means” or “step” clause asspecified in 35 U.S.C. §112, ¶6.

We claim:
 1. A method of communication comprising: modulating at a pointto multi point centralized synchronizing communication controller,according to a modulation method corresponding to a demodulation methodof a wireless client device receiver, a common channel downlinkmulti-carrier transmission including one or more sub-channels carryingdata associated with a first wireless client and one or moresub-channels carrying data associated with a second wireless client;receiving the downlink multi-carrier transmission at a firstnon-regenerative hybrid converter and at a second non-regenerativehybrid converter; shifting the frequency of the downlink multi-carriertransmission from a common distribution frequency to a common wirelessfrequency in both the first hybrid converter and in the second hybridconverter, which common wireless frequency is designated by saidcentralized synchronizing communication controller; andnon-regeneratively transmitting the frequency-shifted downlinkmulti-carrier transmission from both the first hybrid converter and fromthe second hybrid converter.
 2. The method of claim 1, furthercomprising the steps of: receiving by the first wireless client thefrequency-shifted downlink multi-carrier transmission from the firsthybrid converter, and receiving by the second wireless client thefrequency-shifted downlink multi carrier transmission from the secondhybrid converter; and transmitting an upload multi-carrier transmissionto the air by the first wireless client in accordance with transmissionsynchronization and bandwidth allocation data transferred in a downlinksub-channel associated with the first wireless client.
 3. The method ofclaim 2, further comprising the steps of: receiving the upload multicarrier transmission by the first hybrid converter; andnon-regeneratively shifting the frequency of the received upload multicarrier transmission from the wireless frequency to the wireddistribution frequency.
 4. The method of claim 2, further comprisingmodulating the upload multi carrier transmission by an OFDMA modulationand using an amount of sub-channels that is smaller than the entirecomposition of the OFDMA channel.
 5. The method of claim 2, furthercomprising modulating the upload multi carrier transmission by an OFDMAmodulation and using one sub-channel.
 6. The method of claim 2, whereinthe downlink multi carrier transmission and the upload multi carriertransmission further comprise payloads.
 7. The method of claim 1,further comprising modulating the multi carrier transmissions by an OFDMmodulation or an OFDMA modulation and wherein the centralizedsynchronizing communication controller comprises a MAC used by an IEEE802.16 orthogonal multi carrier modulation.
 8. The method of claim 1,wherein the wireless clients are standard IEEE 802.16 orthogonal multicarrier modulation mobile clients.
 9. The method of claim 1, wherein thefirst and the second hybrid converters have at least partiallyoverlapping coverage areas and the first wireless client is located inthe overlapping coverage area.
 10. The method of claim 9, furthercomprising the steps of: receiving by the first wireless client asuperposition of the transmitted frequency-shifted multi carriertransmissions from the first and from the second hybrid converters; andtransmitting an upload multi carrier transmission to the air by thefirst wireless client.
 11. The method of claim 10, further comprisingthe steps of: receiving the upload multi carrier transmission by thefirst and by the second hybrid converters, and non-regenerativelyshifting the frequency of the upload multi carrier transmission from thewireless frequency to the wired distribution line frequency; andreceiving a non-regenerated superposition of the frequency-shiftedupload multi carrier transmission from the first and the second hybridconverters by the wireless point to multi point centralizedsynchronizing communication controller.
 12. A point to multipointcommunication system comprising: a centralized synchronizingcommunication controller adapted to modulate, according to a modulationmethod corresponding to a demodulation method of a wireless clientdevice receiver, a common channel downlink multicarrier transmissionincluding one or more sub-channels transferring data associated with afirst wireless client and one or more sub-channels transferring dataassociated with a second wireless client; First and secondnon-regenerative bi-directional hybrid converters communicativelycoupled to said controller, via a shared distribution channel, andadapted to non-regeneratively transmit, at a common wireless frequencydesignated by said centralized synchronizing communication controller,the common channel downlink multicarrier transmission to first andsecond wireless clients, and wherein said controller is further adaptedto modulate, on the one or more sub-channels associated with a givenwireless client, transmission synchronization and bandwidth allocationdata used by the given wireless client for upload transmission.
 13. Thesystem of claim 12, wherein said controller and hybrid converters arecommunicatively coupled though a shared signal wired distribution lineselected from the group of: twisted pair, coax, fiber optics, and acombination thereof.
 14. The system of claim 12, wherein modulation isorthogonal multi carrier modulation, and wherein the centralizedsynchronizing communication controller further comprises a MAC used byan IEEE 802.16 orthogonal multi carrier modulation.
 15. The system ofclaim 12, wherein the wireless clients are standard IEEE 802.16orthogonal multi carrier modulation mobile clients.
 16. The system ofclaim 12, wherein the first and the second bi-directional hybridconverters have at least partially overlapping coverage areas and thefirst wireless client is located in the overlapping coverage area.
 17. Apoint to multi point communication system comprising: a centralizedsynchronizing communication controller, connected to a shared wireddistribution line, configured to: (1) determine transmissionsynchronization and bandwidth allocation between a first wireless clientand a second wireless client; (2) modulate, according to a modulationmethod corresponding to a demodulation method of a wireless clientdevice receiver, a downlink multi-carrier transmission including dataassociated with a first wireless client and data associated with asecond wireless client and further including the determinedsynchronization and bandwidth allocation data; and (3) transmitting thedownlink transmission on said shared wired distribution line at a firstfrequency; a first and a second non-regenerative hybrid converterscommunicatively connected to said shared wired distribution line,configured to: (1) receive the downlink multi carrier transmission fromsaid controller over said shared wired distribution line; (2) frequencyshift the downlink transmission to a common wireless frequency suitablefor communication with a wireless client, which common wirelessfrequency is designated by said centralized synchronizing communicationcontroller; and (3) non-regeneratively transmit the shifted signal atthe common wireless frequency to the first wireless client from thefirst non-regenerative hybrid converter and to the second wirelessclient from the second non-regenerative hybrid converter.